In order to maximize passenger comfort and safety, as well as vehicle durability, it has become increasingly important to increase environmental isolation of a passenger compartment of a vehicle from an engine compartment of a vehicle. The isolation of the passenger compartment includes a need to prevent passage of environmental elements such as water, dust, air, and heat, as well as other pollutants, from the engine compartment into the passenger compartment.
However, proper design of a heating ventilation and air conditioning (HVAC) system of the vehicle requires that components of the HVAC system be located in both the engine compartment and the passenger compartment. For example, the HVAC system may include a number of system components in the engine compartment such as a condenser or a compressor, as well as components in the passenger compartment such as an evaporator.
Positioning of the system components in the engine compartment and the passenger compartment makes the task of isolating the passenger compartment from the engine compartment particularly challenging, as a number of conduits of the HVAC system must be disposed through a bulkhead intermediate the engine compartment and the passenger compartment. To provide for efficient assembly of the HVAC system within the vehicle, apertures through the bulkhead must be larger than the respective conduits that pass therethrough, providing a clearance between the conduits and the bulkhead. However, the clearance around the conduits provides for easy passage of fluids and other pollutants from the engine compartment into the passenger compartment.
To militate against the passage of the fluids and the other pollutants, seals are installed in the apertures through the bulkhead and around the conduits, thereby sealing the clearances around the conduits. To ease assembly and accommodate a dimensional variation of the system components such as between the conduits and the apertures, it is desirable to manufacture the seal out of a softer and more flexible material. However, softer materials are less resistant to the passage of fluids, and reduce sealing effectiveness compared to stiffer, less flexible seals. These competing interests require a balance between making the seal soft enough to be easily assembled, and hard enough to provide sufficient sealing effectiveness.
Further complicating the isolation of the passenger compartment is the inclusion of a thermal expansion valve in the bulkhead. The conduits of the passenger compartment and the engine compartment are typically connected through the thermal expansion valve. The thermal expansion valve controls a flow of a refrigerant through the HVAC system based on thermal input to a diaphragm disposed thereon. To prevent undesirable fluctuation in the flow of the refrigerant through the HVAC system, the diaphragm of the thermal expansion valve must be thermally insulated from temperature variations in the engine compartment.
To address these concerns, various sealing configurations for HVAC systems have been utilized. For example, a single seal may be installed around the thermal expansion valve to provide both a sealing between the passenger compartment and the engine compartment, and an insulation of the thermal expansion valve. However, the single seal configuration fails to sufficiently militate against the passage of fluids into the passenger compartment, as the seal must be formed of a softer material and provide clearance to allow easier installation of the HVAC system. In a second configuration, a stiffer secondary seal may be added behind the thermal expansion valve to improve a sealing between the passenger compartment and the engine compartment. Alternatively, a first seal may be installed behind the thermal expansion valve, while a separate cap is fitted to the diaphragm of the thermal expansion valve. The secondary seal and separate cap designs each require increased manufacturing costs, as multiple components are required to achieve sufficient sealing between the passenger compartment and the engine compartment, and the insulation of the diaphragm.
Accordingly, there is a need in the art for an economical seal for refrigerant conduits and valves in a vehicle, wherein sealing performance and reliability requirements are maximized, while also providing thermal insulation of a thermal expansion valve.